1. Field of the Invention
The present invention relates to the cleaning of various containers which are used to hold beverages of various kinds and from which the beverage is dispensed to the customer and particularly to the cleaning and sanitizing of the interior surfaces of such containers.
2. Description of Prior Art
While not limited thereto in its utility, the present invention is particularly well suited for use in the cleaning of the internal surfaces of beer kegs. Such kegs are typically provided with a fitting which remains in one end of the keg. This fitting includes the usual check valves which permit the keg to be charged and subsequently emptied. The fitting also includes a riser pipe or spear which extends from the fitting to a point adjacent the opposite end of the keg. The present invention is specifically directed to such a keg which includes a heat exchange unit secured permanently internally thereof which when activated provides a self cooling of the beverage contained within the keg, for example, beer. This eliminates the necessity of maintaining the keg in a refrigerated area and allowing the contents of the keg to be dispensed without the necessity of refrigerated rooms or refrigeration units disposed at the point where the beer is drawn from the keg to be served to a customer.
The obtaining of satisfactory cleaning of such containers and particularly of beer kegs subsequent to their use is a problem of long standing in the art. Various techniques have been invented in an attempt to solve this problem. One such technique is the utilization of a cleaning fluid which is injected to wash the internal keg surfaces through the keg fitting riser pipe and is injected into the barrel or keg under pressure from the end of the riser pipe. The thus injected cleaning fluid will be deflected off of the bottom of the keg which faces the open end of the riser pipe and then will flow down the inside wall of the keg. The cleaning action which is achieved is enhanced by imparting a suitable shape to the interior wall of the keg. The cleaning fluid is removed from the keg via the passage in the keg fitting through which compressed gas is introduced during normal usage. The degree of cleaning achieved with this technique depends on several factors; such as design of the keg, the distance between the end of the riser pipe and the facing keg wall, the pressure of the cleaning fluid and the quantity of the cleaning fluid. Because it is not typically possible to accurately control all of these variables the desired cleaning and sterilizing effect has not always been achieved. Another problem exists in that it is very difficult to obtain cleaning of the exterior surface of the riser pipe or spear and such has been attempted by reducing the pressure of the cleaning fluid delivered at the end of the cleaning cycle to allow the fluid to flow down the exterior surface the spear.
In order to more effectively obtain cleaning an additional technique has been attempted and is referred to as interval cleaning which requires the modulation of a supply of compressed air such that the air is injected into the cleaning fluid being delivered through the riser pipe in bursts or slugs. This results in the introduction of the cleaning fluid into the keg from the riser pipe in the form of discharges which resemble explosions with the result being that annular shock waves will run along the keg wall from top to bottom. This technique has also proven to be unsatisfactory since there is no way to ensure that all parts of the interior of the keg will be washed by the cleaning fluid.
An additional technique has been to alternately introduce the cleaning fluid through the riser pipe and the keg fitting housing and then to introduce the cleaning fluid through the compressed gas and supply valve of the keg fitting. It is contemplated that when the cleaning fluid is introduced into the keg by way of the compressed gas valve. The fluid will also wash the outer surface of the riser pipe.
Still yet another example of a method and apparatus for cleaning the interior surface of a beverage keg is to introduce the cleaning fluid into the interior surface of the keg and then to set it in turbulent motion by injection of a gaseous or vaporous medium from beneath the surface of the thus introduced cleaning liquid. In addition, the cleaning fluid may be introduced in increments such that the level of the cleaning fluid internally of the keg is increased in step-wise fashion. The gaseous or vaporous medium which causes the turbulence in the cleaning fluid is injected between the incremental steps of addition of cleaning fluid. It is also contemplated to simultaneously inject the cleaning fluid and the gaseous medium into the interior part of the keg to be cleaned.
All of the known prior art processes and apparatus for use in cleaning containers and particularly kegs have one or more deficiencies. The common characteristic of the prior art techniques has been the lack of the ability to ensure that all interior surfaces of the keg can be cleaned and will be contacted by the cleaning fluid. Furthermore, none of the prior art techniques included any means for recharging a self-contained heat exchange unit with a compressed gas such as carbon dioxide as an extension of the cleaning cycle, that is, at the conclusion thereof.